Nanonewsletter No

nanonewsletter No. 28 /// December 2013 www.phantomsnet.net AtMol Special Issue Electron tunnelling manipulation of self- assembled molecular nanostructures Coronene: A Single Molecule Atom Counter Measuring the conductance of single molecular wires as a function of the electron energy Synthesis of Y-Shaped Polyarenes, Crushed Fullerenes and Nanographene Fragments dear readers, Dear Readers, The AtMol Integrated Project (EU/ICT/FET) is currently establishing a comprehensive process flow for fabricating a molecular chip, i.e. a molecular processing unit comprising a single molecule connected to external mesoscopic electrodes with atomic scale precision and preserving the integrity of the gates down to the atomic level after the encapsulation. This E-nano Newsletter special issue contains four articles providing new insights on this hot research topic in Europe, in particular for the fabrication of future generations of electronic circuits with components miniaturized down to atomic scale. Detailed information about the project, further reading documents and AtMol workshop series contributions could be found at www.atmol.eu. We would like to thank all the authors who contributed to this issue as well as the European Commission for the financial support (ICT/FET FP7 AtMol project no. 270028). > Dr. Antonio Correia Editor - Phantoms Foundation contents 05 > nanoresearch - AtMol. Electron tunnelling manipulation of self-assembled molecular nanostructures /// F. Moresco, A.Nickel, R. Ohmann, J. Meyer, M. Grisolia, C. Joachim and G.Cuniberti 13 > nanoresearch - AtMol. Coronene: A Single Molecule Atom Counter /// C. Manzano, W. H. Soe, M. Hliwa, M. Grisolia, H. S. Wong and C. Joachim 21 > nanoresearch - AtMol. Measuring the conductance of single molecular wires as a function of the electron energy /// M.Koch, F. Ample, C. Joachim and L. Grill 29 > AtMol publications. Further reading 33 > nanoresearch - AtMol. Synthesis of Y-Shaped Polyarenes, Crushed Fullerenes and Nanographene Fragments /// P. Calleja, R. Dorel, P. Mc Gonigal, P. de Mendoza, and A. M. Echavarren editorial information No. 28 December 2013. Published by Phantoms Foundation (Spain) editor > Dr. Antonio Correia > [email protected] assistant editors > Maite Fernández, Conchi Narros and José Luis Roldán. 1500 copies of this issue have been printed. Full color newsletter available at: www.phantomsnet.net/Foundation/newsletter.php For any question please contact the editor at: [email protected] editorial board > Adriana Gil (Nanotec S.L., Spain), Christian Joachim (CEMES-CNRS, France), Ron Reifenberger (Purdue University, USA), Stephan Roche (ICN-CIN2, Spain), Juan José Sáenz (UAM, Spain), Pedro A. Serena (ICMM-CSIC, Spain), Didier Tonneau (CNRS-CINaM Université de la Méditerranée, France) and Rainer Waser (Research Center Julich, Germany). deadline for manuscript submission depósito legal printing Issue No. 29: March 31, 2014 legal deposit Gráficas Issue No. 30: April 30, 2014 BI-2194/2011 Indauchu 333 nanoresearch Electron tunnelling manipulation of self-assembled molecular nanostructures Francesca Moresco1, Anja Nickel1, Robin controlled at the atomic scale, can be Ohmann1, Joerg Meyer1, Maricarmen tested by adsorbing specially designed 2 2 Grisolia , Christian Joachim and molecules on a surface in ultra clean 1 Gianaurelio Cuniberti conditions, imaging and manipulating 1 Institute for Materials Science, Max Bergmann them using the tip of an STM. Center of Biomaterials, and Center for Advancing Electronics Dresden, Dresden, Germany In the last few years, the manipulation of 2 Nanosciences Group & MANA Satellite, CEMES- a molecule with the tip apex of a CNRS, Toulouse, France scanning tunneling microscope (STM) has become a well-established technique Several methods were developed in the to study the mechanics of a single molecule on a surface [1-3]. last decades to manipulate molecules using the tip of a scanning tunneling microscope. Single atoms and molecules can be moved on a surface in a controlled way. However, for the development of devices at the nanoscale, it is important to move not only adsorbates one by one, but also structures composed by several molecules. Therefore, a purely electronic excitation method was recently used for the controlled movement of weakly interacting assemblies of few molecules. The adsorption of Acetylbiphenyl Fig. 1 > Schematic representation of the electron molecules on a Au (111) surface and tunnelling manipulation of a windmill nanostructure./ the formation of nanostructured given by four molecules and stabilized by The controlled manipulation of single hydrogen bonding will be described in atoms and molecules on metal surfaces this article. The electron tunnelling by means of the STM tip was developed induced manipulation of these during the last two decades [4-6]. In nanostructures will be presented. particular, STM has proven to be a Depending on the polarity and position versatile tool for the atomic-scale of the applied voltage, the direction of manipulation and the construction of movement can be selected. nanostructures [1, 2, 4-7]. Single atoms and molecules can be precisely positioned by lateral [6] or vertical manipulation [8]. Introduction Different mechanisms of manipulation To develop molecular machines based were developed on metal [6], ultrathin on single molecules, scanning tunneling insulator [9, 10], or semiconductor [11] microscopy (STM) at low temperature, surfaces. Other manipulation techniques with its high resolution and stability, is a employ electric fields [12], or inelastic very convenient technique. Prototypes of tunneling electrons [13]. Voltage pulses molecular machines, which can be were used to desorb or dissociate 555 molecules, to induce conformational through a motion of the molecule, or a changes or chemical reactions [14]. conformational change, or a modification of the electronic structure [13]. In particular, inelastic electron tunneling project induced manipulation is a process where tunneling electrons are injected from the STM tip positioned above the adsorbed molecule, thus moving it. The electron AtMol energy is normally transferred through an excited state, leading to excitation (rotational, vibrational, or electronic), the rate of which is controlled by the applied bias and the tunneling current [3]. In an STM experiment, when an electron tunnels through an adsorbate, inelastic electron scattering may induce elementary electronic or vibrational excitations of the adsorbate [2]. The inelastic electrons transfer energy to the adsorbate. Such energy, stored in the electronic or vibrational excitation of the molecule, can trigger movement or chemical Fig. 2 > Top panel: Molecular structure of the transformation at the atomic scale [2]. Acetylbiphenyl molecule used in the described Therefore, electron tunnelling induced experiments. Bottom panel: STM image of a single Acetylbiphenyl molecule on Au (111) stabilized by a manipulation might be based on two defect./ different excitations depending on the applied bias voltage. At high voltages an Electron tunneling was recently used to electron may transiently occupy an induce the controlled rotational switching electronic excited level of the adsorbate; of a molecular motor [15]. A molecular at low voltages vibrational modes may be motor adsorbed on a gold surface could excited. be rotated in a clockwise or anticlockwise direction by selective inelastic electron Experimentally, electron tunnelling tunnelling through different subunits of the induced manipulation is realized by motor. positioning the STM tip above the location of the molecule at a fixed height. The Electron tunnelling induced manipulation feedback loop can be switched off and the has the advantage to be triggered just by tunnelling current and/or the voltage are electronic excitations and to avoid any increased from imaging to manipulation direct mechanical interactions of the STM parameters. The electrons can be injected tip apex with the adsorbate. Moreover, either from the tip or from the substrate being mechanically less destructive than depending on bias polarity. The point in common lateral manipulation, it can be time at which a change in the molecule successfully applied to the controlled happens is recorded by monitoring the manipulation of weakly bonded tunnelling current versus time. A sudden supramolecular assemblies [16]. Recently, change in current is indicative of the it was demonstrated that it is possible to success of the manipulation. These manipulate in a controlled way sudden jumps are caused by changes in supramolecular structure by electron the apparent height of the molecule either tunnelling induced manipulation [16]. 666 In this article, we will describe the adsorption of Acetylbiphenyl molecules on the Au (111) surface and the formation of windmill nanostructures studied by STM at low temperature. In project Fig. 1 the voltage pulse manipulation of the windmill structure is schematically shown. By applying voltage pulses just AtMol on one selected molecule of the structure, it is possible to move the complete supramolecular assembly to a chosen position on the surface without destroying it. Experimental details The 4-Acetylbiphenyl (ABP) molecules (Fig. 2) were studied on the Au (111) surface with a low-temperature STM (5 K) under ultra-high vacuum conditions Fig. 3 > Top panel: STM image of an island of (<10-10 mbar). The gold single crystal disordered ABP molecules on Au (111). Bottom surface was cleaned by repeated cycles panel: Linescan

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